Among the most important features of an image is its color distribution. Some research has been done about extracting dominant colors from a particular image and then describing how those colors are distributed across the image. Also a few comparison methods have been developed for comparing images based on the extracted colors and their distribution.
All known existing color search implementations assume that the user knows exactly all colors he or she wishes to search for, and needs to retrieve images containing only those colors. In many cases this is not true, or possible; and the user may want to find images containing one or more known colors and one or more ‘other,’ unknown or unspecified colors. This scenario is not yet addressed by existing color comparisons methods, and therefore is not yet implemented by existing computer programs or web search engines.